1. Field of the Invention
The present invention relates to a lubricating oil feed passage structure formed in a crank shaft of an internal combustion engine, more particularly, to a lubricating oil feed passage for feeding a lubricating oil to a connection surface for connection with a connecting rod connected to a crank pin.
2. Background Art
Heretofore, taught is a lubricating oil feed passage structure formed in a crank shaft of an internal combustion engine for feeding a lubricating oil to a connection surface. The connection surface is in connection with a large end portion of a connecting rod that is connected to a crank pin. The foregoing disclosed in Japanese Unexamined Patent Publication No. Hei 9-53704.
According to the technique disclosed in the publication, as shown in FIG. 2, a driving sprocket d, on which is entrained a cam chain for driving a cam shaft, is implemented for driving intake and exhaust valves. A primary driving gear e and an oil pump or cooling water pump driving gear f are splined to an end portion of a crank shaft a, which extends from a crank journal b toward a crank case cover c. They are tightened and fixed with a nut g through a washer.
In the crank shaft a, there are formed a lubricating oil passage having a passage i extending coaxially with the crank shaft a, a passage m extending from the passage i and reaching a hollow portion k of a crank pin j, and a passage p which extends from the hollow portion k and is open to a connecting rod connection surface of the crank pin j with a large end portion n of the connecting rod being connected to the connection surface through a bearing. A tip end of the crank shaft end portion is received in a lubricating oil chamber r formed in the crank case cover c. An oil seal s, which is fixed to an open end of the lubricating oil chamber r, comes into sliding contact with an outer periphery of the tip end of the crank shaft end portion to prevent the lubricating oil present in the lubricating oil chamber from leaking through the tip end outer periphery.
Via the lubricating oil feed structure formed in the crank shaft a, the lubricating oil, fed from an oil pump into the lubricating oil chamber r through a filter, flows through an opening formed in the end face of the crank shaft end portion. The lubricating oil flows further through the lubricating oil passages i, m, k, p, and is fed between the connecting rod connection surface of the crank pin j and the bearing for the large connecting rod end portion n to lubricate the sliding portion.
In the background art described above, the passage i, formed toward the crank arm h, from the end face of the crank shaft end portion and extending coaxially with the crank shaft a, is a long passage because it passes through a relatively long shaft end portion. In the long shaft and portion are formed the mounting portion for the driving sprocket d, a primary driving gear e, an auxiliary device driving gear f, and the mounting portion for the nut g and the tip end portion extending up to the lubricating oil chamber r, formed in the crank case cover c. Therefore, due to the complex structure, the boring process for forming such a long passage system is very difficult.
In view of the deficiencies of the background art, it is an object of the present invention to provide a lubricating oil feed passage structure wherein a lubricating oil introducing member is mounted to shorten an end portion of the crank shaft and thereby facilitate machining of the lubricating oil passage to be formed in the crank shaft.
A further object of the present invention is to shorten the crank shaft end portion to a greater extent and ensure a fixed state of the torque transfer member by utilizing a bolt which serves as a lubricating oil introducing member and which functions to fix the torque transfer member.
In addition, an object of the present invention is to provide a case where the spacing between the end face of the crank shaft end portion and the lubricating oil chamber differs depending on the model of a vehicle.
These objects and other objects of the present invention are accomplished by providing a lubricating oil feed passage structure in a crank shaft, having a lubricating oil passage formed in the crank shaft which has a crank pin with a connecting rod connected thereto, the lubricating oil passage having an inlet end and an outlet end which is open to a connection surface for connection with the connecting rod of the crank pin; a lubricating oil introducing member mounted at an end portion of the crank shaft so as to project in an axial direction of the crank shaft from an end face of the crank shaft end portion; and a lubricating oil introducing passage formed axially through the lubricating oil introducing member and connected to the inlet end.
Therefore, since the lubricating oil is introduced into the lubricating oil passage of the crank shaft through the lubricating oil introducing passage formed in the lubricating oil introducing member which is mounted so as to project in the axial direction of the crank shaft from an end face of the crank shaft end portion, the length of the crank shaft end portion becomes smaller than in the background art device by an amount corresponding to the length of the lubricating oil introducing member projecting from the end face of the crank shaft end portion, so that the length of the lubricating oil passage formed in the shaft end portion becomes smaller and hence the machining for the lubricating oil passage to be formed in the crank shaft becomes easier.
Moreover, in the lubricating oil feed passage structure, the lubricating oil introducing member is a bolt which prevents the torque member from moving in the axial direction of the crank shaft, and thus the bolt is utilized also as a lubricating oil introducing member, so the length of the crank shaft end portion can be made smaller by an amount corresponding to the length of the bolt projecting from the end face of the crank shaft end portion. In the projecting bolt length is also included the length of the nut mounting portion in the background art. As a result, the length of the lubricating oil passage formed in the crank shaft becomes still smaller and therefore the machining for the passage becomes easier. Moreover, since the torque transfer member is tightened with the bolt, the bolt becomes difficult to loosen under the action of an elastic force developed in the bolt itself, whereby the movement of the torque transfer member in the axial direction of the crank shaft is prevented more positively.
Furthermore, in the lubricating oil feed passage structure, the head of the aforesaid bolt has a cylindrical portion, which is positioned within the lubricating oil chamber formed in the crank case cover. Thus, since the cylindrical bolt head portion gets into the lubricating oil chamber, even in the case where the spacing between the end face of the crank shaft end portion and the lubricating oil chamber differs, depending on the model of a vehicle for example, it is possible to cope with such a case easily by providing a plurality of bolts different in the length of the cylindrical portion, therefore, the need of changing the crank shaft is not required.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.